Arc furnaces are used for the reprocessing of steel scrap, the steel scrap being heated and finally melted by means of an electrode and a burning arc. Such an arc furnace comprises a furnace vessel for melting the steel and a cover for closing the furnace vessel during the melting process. In order to charge the furnace with scrap, and maintain the furnace, it is necessary to open the furnace vessel and therefore swivel the cover open. To this end, the cover is connected via a pivot cylinder to a swivel unit, which is also referred to as a portal. The cover is first raised by the pivot cylinder, thereby releasing it from the furnace vessel. It can then be swiveled away laterally from the furnace vessel by means of the swivel unit.
In order to empty the liquid steel from the furnace vessel, the furnace vessel is tilted about an axis which is perpendicular to the longitudinal axis of the furnace. For this purpose, the furnace vessel is mounted in a cradle which has a rolling contact path for this tilting movement. During such a tilting movement, the swivel unit with the cover is also tilted.